In recent years, some of mobile electronic devices such as mobile phones and smartphones have a function to acquire information about their own positions. From a viewpoint of ensuring children's safety, a service that provides a current position of a child in response to a request from one of his or her parents is also being pervaded, for example (refer to Patent Literature 1).
Patent Literature 1 discloses a system in which a position information service center receives current position information identified by a GPS receiver mounted on a terminal held by a child and responds the current position information about the child in reply to an inquiry from a mobile phone held by the parent.